You chose the Efficiency of - a PACKED PLUNGER PUMP,
you have the least pressure pulsation - from a variable stroke metering pump
(Excluding "lost motion - limited back stock" machines).

TECH NOTE: (not necessary to read these highlighted areas)
The distance between the end of the plunger stoke, and the cylinder head, plus the volume in the suction and discharge check valve pockets, are together, less than a quarter of the dad volume of a diaphragm head pump, 1/4 the inefficiency of a diaphragm head.
Because of this high efficiency of plunger pumps, the liquid is accelerated progressively, prevents pressure shocks, & provides a smoother flow.

An extruder producing foam insulation for pipe cover, needs a constant feed of foaming agent. This is like a refrigerant. These foaming liquids are highly compressible, and despite the high efficiency of plunger pumps, in general, it is necessary to intercept the decompression shock wave with a "flow through" .

ANSWER
A separate connection, in and out, "flow through", 70 times the volume of one stroke of the pump, rated at 2250 psi (150 Bar) 3/8" pump connection & 1/8" system connection, available off the shelf.

THE RULE OF "2:6:3:1" ratio of cross sectional areas inside the pipes. More flow and pressure stabilization is achieved by having: 1) A pipe sized for 0.6 meters per sec. constant velocity to the suction dampener . 2) A pipe sized for peak velocity from suction dampener to pump inlet check valve. 3) Pipe for peak velocity from pump discharge to dampener . 4) Sized for 3 meters per sec from dampener for the system.

RESULTS
(1) The CORIOLIS (vibrating tube) mass transfer meter gives ACCURATE READINGS. Instead of being over excited at its natural frequency of 90 Hz.
(2) The ratio of dampener inlet hole size to dampener internal diameter is in excess of 1:6. This ratio gives a "discharge coefficient" which in effect KILLS THE PRESSURE PULSE. The residue of the pressure wave is prevented from escaping from the outlet by the even higher "convergence coefficient".
(3) The flow fluctuations are stabilized to LESS THAN A 1% FLOW SWING by the accumulation capability of the Nitrogen volume.
The right size of pipe, small enough to be "dissipative", does as much to stabilize flow fluctuations, and reduce pressure pulsation, & prevent resonance, as is achieved with "dampeners",and smaller pipe costs less.